In recent years the increase demand by patients for minimal invasive surgery has required surgeons to perform intricate suturing and ligation procedures involving extra corporeal formation of slip-type knots on a suture strand and thereafter pushing the knot along the strand into the operative region.
Pushing a knot through a cannula to form a ligature or suture is well known in the prior art. In U.S. Pat. No. 5,324,298, a knot pushing instrument is described where the instrument utilizes a locking sleeve which is rotated relative to an elongated member in order to captively retain the strand of suture in a slot; thus, when a knot was pushed through a cannula the suture strand was permitted to advance axially through the slot while being captively held within the slot by the locking sleeve. One of the disadvantages in using this type of knot pushing instrument was that the surgeon was required to physically rotate the sleeve while holding that portion of the strand of suture which was to be locked into the slot. During surgical procedures, it is desirable to reduce the manipulations of a surgical instrument by the surgeon and thus reduce the time during which the patient is under anesthesia. Another disadvantage is the expense to manufacture an instrument which consists of two separate parts which must be assembled so as to permit relative rotation between the parts.
Another patent, U.S. Pat. No. 5,269,791, illustrates a knot pushing instrument of the prior art where a conical tapered coil was used at the distal end of the knot pushing instrument. The coil of that invention required the suture strand to be wound between the turns of the coil and the knot thereafter pushed into the operative region by the distal tip of the tapered coil. In order to push a knot with this instrument the surgeon was required to hold the suture strand, the instrument, and then wind the strand around the conical coil. Again, the manipulations required by the surgeon in order to captively retain the strand above the slip-type knot increased the time of the surgery and therefore the length of time under which the patient was kept under anesthesia.
It would therefore be advantageous to provide an inexpensive knot pushing instrument for use in minimum invasive surgery that would permit the surgeon to easily ensnare a strand of suture, captively retain the strand in a slot, and thereafter push the knot into the operative region by axially advancing the suture through the slot.